Insemination with beef bull semen reduces the risk of neosporosis abortion in dairy cows

Different crossbreed pregnancies carried different abortion risks in Neospora-infected dairy cows. This is one of the conclusions obtained from a collaborative study carried out by Universitat de Lleida, CReSA-Universitat Autónoma de Barcelona and Universidad de Zaragoza.

Neosporosis, which is caused by the parasite Neospora caninum (obligate, intracellular protozoan), is one of the most frequent causes of abortion in bovine. Previous studies demonstrated that the use of beef bull semen reduces the risk of abortion in N. caninum-seropositive dairy cows. These results reinforce the idea that differences exist between breeds of beef cattle in terms of their susceptibility to both N. caninum infection and abortion.

A study published by Dr Sonia Almería in the journal Veterinary Parasitology demonstrated that the use of beef bull semen dramatically reduced the risk of abortion in dairy cows (Effects of crossbreed pregnancies on the abortion risk of Neospora caninum-infected dairy cows. Almería S, López-Gatius F, García-Ispierto I, Nogareda C, Bech-Sàbat G, Serrano B, Santolaria P, Yániz JL. Vet Parasitol. 2009 Aug 26;163(4):323-9).

The study was performed on five commercial Holstein-Friesian dairy herds in Northeast Spain with previously confirmed diagnoses of N. caninum infection in aborted foetuses. A total of 1115 pregnancies were included:

  • 482 pregnancies recorded after artificial insemination (AI) with semen from 18 Holstein-Friesian (HF) bulls
  • 633 pregnancies recorded after AI with semen from 27 beef bulls (304 inseminations using semen from Limousin bulls, 191 from Belgian Blue bulls, 89 from Piedmontese bulls and 49 from Charolais bulls).

The most relevant results are summarized next:

  • Abortion rates were 32.2% (155/482) and 15.2% (96/633) for seropositive cows inseminated with HF and beef breed semen, respectively.
  • Logistic regression analysis revealed that herd and the interaction between maternal N. caninum antibody titre and the different crossbreeds as significant factors affecting the abortion rate.
  • Lowest abortion rates, similar to that shown by seronegative animals in the analyzed herds (3.2%, 239/7432), were observed in dams AI using Limousin semen that had low (<30 relative index (RI) units) N. caninum antibody titres (2.1% abortion, 3/145) and these cows were used as reference. Compared to cows used as reference, cows with low N. caninum antibody titres (<30 RI units) showed a similar risk of abortion when inseminated with Piedmontese or Charolais bull semen, but higher risk of abortion when inseminated with HF (17.9 times) or Belgian Blue (7.2 times) bull semen.
  • All cows with high N. caninum antibody titres (>=30 RI units) had a higher risk of abortion, ranging from 8.9 times (cows inseminated with Limousin semen) to 37.8 times (cows inseminated with Piedmontese semen), compared to the cows used as reference.

As conclusions:

  • The study showed that different crossbreed pregnancies carried different abortion risks in Neospora-infected dairy cows.
  • The use of beef bull semen dramatically reduced the risk of abortion in dairy cows, especially if Limousin breed semen was used.
  • This reduction was found to be dependent on the N. caninum antibody titre such that the lowest incidence of abortions was recorded in Limousin semen inseminated cows with low antibody titres.

Insemination of Neospora-seropositive cows with beef bull semen could both reduce the risk of abortion and avoid breeding replacements for infected cattle.

To contact with the author of this paper:

Dr Sonia Almería de la Merced
Investigator                                                                      
Parasitology and Entomology Unit (CReSA)
Email: sonia.almeria@uab.cat
Edifici CReSA. Campus UAB
08193 Bellaterra (Barcelona) Spain

For more information about this publication and related articles: sciencedirect

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